a = {
    'jack':4098,
    'obj1':'yqy1',
     'obj2':'yqy2',
      'obj3':'yqy3',
       'obj4':'yqy4'
}
print(a.pop('jack1','没有'))
a.popitem()
print(a)
a.popitem()
print(a)
a.popitem()
print(a)

a = {'one':1,'two':2,'three':3}
del a['one']
print(a)
a = {'one':1,'two':2,'three':3}
a.clear()
print(a)
a = {'one':1,'two':2,'three':3}
a.keys()
a.values()
a.items()

a = {'one':1,'two':2,'three':3}
b = a.keys()
# 转换成列表
list(b)   
# 转换成集合  
set(b)
# 转换成元组
tuple(b)